1. Field of the Invention
Exemplary embodiments of the present invention generally relate to a lubricant supplier, a process cartridge including the lubricant supplier, and an image forming apparatus including the lubricant supplier, and more particularly, to a lubricant supplier having a lubricant regulating blade regulating a layer of lubricant supplied to a surface of an image forming member, a process cartridge including the lubricant supplier, and an image forming apparatus including the lubricant supplier.
2. Discussion of the Related Art
Related-art electrophotographic image forming apparatuses generally use a cleaning device to remove residual toner remaining on a surface of an image bearing member after a toner image formed on the surface of the image bearing member is transferred onto an image receiving member or a recording medium. By so doing, the image bearing member is cleared and ready for a subsequent image forming operation. The cleaning device generally includes an elastic cleaning blade, typically made of a material such as polyurethane rubber, which has a simple structure and sufficient performance in toner removal.
To reduce a coefficient of friction between the cleaning blade and the surface of the image bearing member, some related-art electrophotographic image forming apparatuses further include a lubricant supplier that supplies lubricant such as fatty acid composed of metal salts onto the surface of the image bearing member.
Insufficient lubrication of the surface of the image bearing member cannot reduce the coefficient of friction sufficiently, and results in, for example, curling of the edge of the cleaning blade and/or a shorter life for the image bearing member.
By contrast, excessive lubrication can contaminate components and units disposed around the image bearing member, which also causes various problems such as defective images produced when the lubricant adheres to a charging member, a developer bearing member, and the like.
Accordingly, it is important to control such a lubricant supplier so as to supply only the proper amount of lubricant to an image bearing member.
Some related-art image forming apparatuses are designed to supply lubricant to a surface of an image bearing member at a position upstream from a contact portion of a cleaning blade with respect to the image bearing member in a direction of movement of the surface of the image bearing member. Since the cleaning blade provided in such an image forming apparatus can regulate a depth of the lubricant on the surface of the image bearing member, a lubricant regulating member as such is not required in the image forming apparatus.
The above-described configuration, however, causes the lubricant, together with residual toner on the surface of the image bearing member, to enter the contact portion of the cleaning blade with respect to the image bearing member, and therefore amounts of lubricant may be uneven on different local portions on the surface of the image bearing member. Specifically, the amounts of lubricant may be uneven on the surface of the image bearing member between portions with residual toner and portions without residual toner, and therefore, the image bearing member may have portions with insufficient lubricant and portions with excess lubricant. Accordingly, some local portions on the surface of the image bearing member may be susceptible to the above-described problems.
Further, some lubricant adhering to residual toner is removed with the residual toner by the action of the above-described cleaning blade. Since it is difficult to know how much lubricant is removed with the residual toner, it is hard to control amounts of lubricant supplied to and consumed on the surface of the image bearing member, thereby causing the above-described inconvenience.
Among various techniques to eliminate the above-described disadvantages, some related-art image forming apparatuses employ techniques that provide a structure in which a lubricant supplying unit is placed at a downstream side of a contact portion of a cleaning blade in a direction of movement of a surface of an image bearing member, and a lubricant regulating member is arranged at a downstream side of the lubricant supplying unit. With the above-described structure, the surface of the image bearing member is clean before application of lubricant, and therefore the lubricant can be sufficiently applied and regulated to form a layer of uniform thickness thereon. In addition, since the lubricant may stay on the surface of the image bearing member when the residual toner is removed by the cleaning blade, an amount of supply of the lubricant and/or an amount of consumption thereof can be controlled easily.
The lubricant regulating member of these techniques is a blade type supported either in a counter manner or a trailing manner. That is, when a counter-type lubricant regulating blade is used, a supporting member that supports the counter-type lubricant regulating blade is disposed downstream in the direction of movement of the surface of the image bearing member, from a contact portion on the surface of the image bearing member where a ridge line part of the counter-type lubricant regulating blade contacts thereon. By contrast, when a trailing-type lubricant regulating blade is used, the supporting member is disposed upstream from the contact portion in the direction of movement of the surface of the image bearing member.
With increasing demand for longer-lasting, maintenance-free image forming apparatuses, it is desirable that the performance of the lubricant regulating blade is maintained throughout the life of the lubricant regulating blade so as to reduce over time the occurrence of failures or disadvantages such as adhesion of lubricant to the components and units disposed around the image bearing member.
However, when contacting the surface of the image bearing member, the lubricant regulating blade is excited to generate vibration called “self-excited vibration.” The self-excited vibration exciting a lubricant regulating blade is generated by a stick-slip vibration. The stick-slip vibration is a vibration frequently repeated between a stick motion, in which the lubricant regulating blade is held in contact with the surface of the image bearing member and fully functional, and a slip motion in which the lubricant regulating blade may not be fully functional. When compared to when no stick-slip motion or vibration is generated, the contact portion of the lubricant regulating blade is more heavily abraded when the stick-slip motion or vibration is generated. Heavier abrasion of the lubricant regulating blade increases an amount of lubricant passing through the contact portion with respect to the surface of the image bearing member, which can cause an amount of lubricant applied to the surface of the image bearing member to exceed an appropriate amount, and therefore defective images can easily be produced at an early stage.
As described above, a related-art lubricant regulating blade generating the stick-slip vibration cannot reduce an amount of abrasion due to time or age, which makes it difficult to maintain the lubricant regulating blade for long, and therefore the defective images can be produced easily.
The above-described problems occur not only when the related-art lubricant regulating blade contacts the surface of the image bearing member but also when the blade contacts a different material to which lubricant is applied. That is, even when the related-art lubricant regulating blade is held in contact with a component or unit other than the image bearing member, the slip-stick vibration can be generated, the amount of abrasion can increase, an amount of lubricant adhering to the components or unit around or in the vicinity of the component contacting the related-art lubricant regulating blade also increases, and as a result, various problems can be caused.